1. Field of the Invention
The present invention relates to a one-dimensional or two-dimensional spatial light modulator array to be provided on an on-demand digital exposure system employed in a photolithography process, an image forming apparatus employing digital exposure, a projection display device such as a projector or the like, and a microdisplay device such as a head-mount display.
2. Description of the Related Art
JP-A-10-39239, JP-A-2002-214543, JP-T-9-510797 and JP-A-7-311391 can be mentioned as known publications in this field.
Among the inventions described in these documents, the invention of JP-A-10-39239 enables provision of a shutter drive circuit or the like on a substrate without involvement of an essential drop in the numerical aperture of the lens, and can be said to be typical of such inventions. To this end, there are provided a microlens for converging light for converging light on an light modulation section formed from a micro-electromechanical element [a micro-electromechanical element formed by means of a micromachine technology is simply called MEM (Micro-Electromechanical) and will be hereinafter referred to as an “MEM light modulation section”]; a substrate on which the light converged by the microlens falls and has a through hole for permitting passage of the light; and a shutter provided on a substrate for controlling passage and blockage of the light having fallen on the through hole.
Such a configuration enables a reduction in the ratio of an opening section of the through hole to the entire surface of the substrate as compared with the ratio of a conventional counterpart without involvement of a drop in the numerical aperture of the lens, assurance of a space to be used for providing a drive circuit or the like on the substrate, a reduction in a distance over which the shutter is actuated, and easy opening and closing action of the shutter by means of electrostatic attractive force.
Therefore, a simpler process can be employed to manufacture a space spatial light modulator which involves little chance of faulty operation. A high-contrast image or the like can be formed on a screen through use of the space spatial light modulator.
An invention of JP-A-2002-214543 is directed toward a device comprising a light-transmission substrate and a circuit panel having a fixed array of transistors, wherein the transistors are fixed to a substrate by means of a bonding layer, connected together by means of conductive row lines and conductive column lines, and connected to an array of pixel electrodes. The device is further provided with liquid-crystal material interposed between a first panel and an opposing electrode of a second panel parallel to the first panel, wherein the first panel is formed from the surface of an essential monocrystal silicon material of the circuit panel. The pixel electrode is positioned between the first panel and the light-transmission substrate, and an electric field or signal-which is generated by the respective electrodes and applied to the liquid-crystal material-changes the optical characteristic of the liquid-crystal material.
An invention of JP-T-9-510797 is directed toward a method for manufacturing an active matrix display. The method comprises: forming an array of transistor circuits through use of a semiconductor layer provided on a first substrate; forming opening sections for limiting pixel electrode areas in the semiconductor layer; forming an array of pixel electrodes in the respective pixel electrode areas; electrically coupling the respective pixel electrodes to one of the transistor circuits; forming an insulation layer on the transistor circuit; forming a light-shielding material on the transistors and the insulation layer; and transferring the transistor circuits, the array of pixel electrodes, and the light-shielding layer from the first substrate to the second substrate. The first substrate is an SOI substrate, and a circuit is transferred on the transparent substrate, whereby an Si substrate is removed by means of etching.
An invention of JP-A-7-311391 is directed toward a method for manufacturing a transmissive LCD device from a high-performance monocrystalline silicon substrate possessing superior field-effect electron mobility. The method comprises: a first step of forming an epitaxial layer of a polycrystalline section in an area on a monocrystalline silicon substrate where pixel openings are to be formed and an epitaxial layer of a monocrystalline section in another area on the monocrystalline silicon substrate; a second step of forming a switching transistor section and a peripheral circuit section for driving purpose on the epitaxial layer of the monocrystalline section and eliminating the epitaxial layer of the polycrystal line section through etching; a third step of forming an embedded layer from transmissive resin in the area from which the epitaxial layer of the polycrystalline section has been removed and subsequently forming a pixel electrode section on the embedded layer; a fourth step of laminating a highly-flat mount glass on the surface of a monocrystalline silicon substrate and adhesively holding the thus-laminated substrate; a fifth step of grinding and abrading a back of the monocrystalline silicon substrate and etching the silicon substrate, as required, to thus expose the back of the embedded layer and form a polycrystalline silicon frame from the epitaxial layer of the monocrystalline section; and a sixth step of laminating the back of the monocrystalline silicon frame to a color filter substrate or a lower glass substrate by means of a transparent adhesive.
However, the invention of JP-A-10-39239 is configured such that an opening section (through hole) for permitting transmission of light is formed in an opaque substrate (e.g., an Si substrate). Hence, the invention suffers from a drawback of a limitation imposed on miniaturization and integrity, as well as complication of a process, thus increasing costs.
Since the invention of JP-A-2002-214543 employs a liquid-crystal element, light originating from a backlight is caused to pass through a plurality of layers, such as a polarizing plate and a filter, thereby raising a problem of a drop in efficiency for light utilization. Further, sealing of liquid crystal between two substrates and orientation of the liquid crystal results in difficulty in increasing the area of the liquid-crystal element. Moreover, light is caused to pass through the orientated liquid-crystal molecules, thereby introducing drawbacks, such as a decrease in the field of view or low responsiveness.
Further, the invention of JP-T-9-510797 also employs a liquid-crystal element, and hence the above-described drawbacks apply to the invention, as well. Further, since the pixel electrode is formed in the opening section, there is no degree of freedom in manufacture, thus posing difficulty in manufacture of the display. Particularly when a microlens array to be described later is used, manufacture of the display becomes difficult. Moreover, since the light-shielding layer and the pixel electrode are indispensable configurations, manufacturing processes become complicated, thus adding to costs.
The invention of JP-A-7-311391 employs a liquid-crystal element as well, and hence the foregoing drawbacks are applied to the invention. Moreover, the method requires the fifth step of forming the monocrystalline silicon frame from the epitaxial layer of the monocrystalline section; and the sixth step for laminating the color filter substrate or the lower glass substrate on the back of the monocrystalline silicon frame by means of a transparent adhesive, and hence manufacturing processes become complicated and costs become high.